Patent literature 1 as described below discloses an air conditioner equipped with an indoor-side air heat exchanger, an outdoor-side air heat exchanger and a bypass circuit. Meanwhile, Patent literature 2 discloses a heat pump type hot-water supply outdoor unit equipped with an water heat exchanger for exchanging heat between water and refrigerant, an outdoor unit side air heat exchanger and a bypass circuit. In the air conditioner of Patent literature 1, by use of the bypass circuit at the time of defrosting, defrosting is performed by making high-temperature and high-pressure refrigerant be bypassed behind the outdoor unit side air heat exchanger without making the high-temperature and high-pressure refrigerant flow on the indoor unit side, thereby the defrosting efficiency is improved. In the heat pump type hot-water supply outdoor unit of Patent literature 2, the water heat exchanger is prevented from freezing by making the refrigerant be bypassed without making the refrigerant flow in the water heat exchanger at the time of defrosting by use of the bypass circuit and an expansion valve, and the water heat exchanger is prevented from freezing by decreasing a refrigerant amount to be flown in the water heat exchanger by the bypass circuit. However, there is no description in Patent literatures 1 and 2 that the water heat exchanger is prevented from freezing by defrosting through making the bypassed refrigerant be flown in the water heat exchanger on the indoor unit side by use of the bypass circuit at the time of defrosting, and a high-efficiency operation at the time of defrosting by performing heat exchange in the water heat exchanger.